Fig. 1.

LC-tandem MS analysis of a whole homogenate from Drosophila. A The raw LC-tandem MS data showing the detection of the 3 peptides in scheduled time windows at characteristic retention times. B and C The raw data are analyzed with the program Pinpoint, which finds and integrates the chromatographic peaks via the overlap of the selected reactions. Only 2 peptides are shown because of space. D The amount of each protein is determined by normalizing to a known amount of bovine serum albumin added to the sample as a non-endogenous internal standard. It is notable that the 50% decrease in catalase abundance expected in Drosophila heterozygous for catalase is observed